Fastener applying device

ABSTRACT

Valving structure for a fastener applying device including a manually responsive member which is effective to initiate a working cycle by causing the main valve to open, and a pneumatically actuated member, effective after the main valve has opened to cause the main valve to close automatically and to maintain it closed even though the manually responsive member remains actuated. A passage including a check valve receives fluid under pressure and communicates with the pneumatically actuated member.

May 1, 1973 ..227/130 X .227/130 X Fehrs..........,... .....................227/l30 3,494,530 2/1970 3,527,142 9/1970 Obergfell... 3,583,496 6/1971 [54] F ASTENER APPLYING DEVICE [75] Inventor: Carl T. Becht, Cincinnati, Ohio [73] Assignee: Senco Products Inc., Cincinnati,

Primary Examiner--Granville Y. Custer, Jr. Attorney-John W. Melville et al.

Ohio

[22] Filed: Aug. 25, 1971 ABSTRACT 21 Appl. No.: 174,677

Valving structure for a fastener applying device including a manually responsive member which is effecmh c r Ha "fie "HS Lh C d s m UhF 1]] 2 8 555 [[1 mm MU .x .2

tive to initiate a working cycle by causing the main 227/130 valve to open, and a pneumatically actuated member, effective after the main valve has opened to cause the References Cited main valve to close automatically and tomaintain it closed even though the manually responsive member remains actuated. A passage including a check valve receives fluid under pressure and communicates with the pneumatically actuated member.

227/ l 30 X 14 Claims, 7 Drawing Figures UNlTED STATES PATENTS 3,313,213 4/1967 Wandel 3,375,758 4/1968 Novak et al. 3,405,602 10/1968 Novak I llllaw w FASTENER APPLYING DEVICE BACKGROUND OF THE INVENTION This invention relates to a pneumatic fastener applying device, and particularly to a valving structure such that the tool will execute a complete working cycle upon actuation of the trigger or other control device.

As used in the specification, the phrase fastener applying device" is intended to refer to a tool adapted to be connected to a supply of compressed fluid, generally compressed air. The tool includes a working cylinder with a piston slidable therein in a working cycle. For purposes of this invention, a working cycle includes a single working or downward stroke by the piston which is effective to fully drive a single fastener. The cycle also includes a return stroke in which the piston is fully returned to its starting position in preparation for a further cycle.

Pneumatic fastener applying devices of the type under consideration generally include a pneumatically actuated main valve structure. This main valve is movable to an opened position wherein it will admit compressed air or fluid into the working cylinder above the piston to drive it in the working stroke. In the closed position, the main valve is effective to open an exhaust passage for the working cylinder above the piston, per mitting the piston to be returned to its original position.

The pneumatic main valve is moved from its closed position to the opened position and vice versa by a remote valving structure generally actuated by a trigger.

Exemplary tools of the prior art are shown in US. 7

Pat. Nos. 2,954,009 issued Sept. 27, 1960 in the name of A. G. Juilfs; U. S. Pat. No. 3,170,487 dated Feb. 23, 1965 in the name of A. G. Juilfs et al.; and Re. Pat. No. 26,262 dated Sept. 5, 1967 in the name of A. G. Juilfs. According to all of these patents, the actuation of the trigger or manual control by the operator is effective to open the main valve of the tool and drive the piston in a working stroke. The piston will remain at the bottom of the working stroke so long as the trigger or manual control remains actuated.

Again, according to each of these patents, the return stroke of the working piston takes place upon release of the trigger or manual control which, as indicated earlier, is effective to cause the main valve to close and exhaust the working cylinder above the piston. According to thetirst patent noted above, the return stroke of the working cycle is effected by a spring, while according to the last two mentioned patents, the return stroke is accomplished pneumatically.

A series of subsequent patents relating to pneumatic fastener applying devices teach a valving structure which, upon actuation of the trigger or manual control, is effective to initiate the working stroke of a cycle. These patents go on to teach structure which will automatically close and then reopen the main valve so long as the trigger remains actuated. These tools are frequently referred to in the art as auto fire" tools.

Exemplary United States patents teaching an automatically reciprocating pneumatic fastener applying device would include US. Pat. Nos. 3,278,102 dated Oct. 11, 1966 in the name of C. Siegmann; 3,278,103 dated Oct. 11, 1966 in the name of G. C. .luilfs et al.; and 3,278,104 dated Oct. 11, 1966 in the name ofC. T. Becht et al.

The art has now recognized the desirability of a pneumatic fastener applying device having a mode of operation which might be considered as in between the two known modes described above. Such tools may be described as a single cycle or cycle through tool. In other words, such a tool will, upon actuation of the trigger or manual control device, execute automatically a complete cycle including both a working and a return stroke.

Such a mode of operation is desirable from a number of standpoints. In the first place, as the size and power of pneumatic fastener applying devices increases, consumption of air becomes more of a problem. It is possible to design a cycle through tool which will use considerably less air for the driving of a given sized fastener.

Secondly, in order to insure the complete driving of a fastener it is often customary for the end of the fastener driver blade at the bottom of the working stroke to project slightly beyond the nose piece of the tool. In upholstery work, for example, this projection can damage the fabric if the operator is not careful. Hence, it would be desirable to have the piston automatically return to eliminate this possibility.

An exemplary cycle through tool is taught in U.S. Pat. No. 3,353,453, issued on Nov. 21, 1967 in the name of Howard B. Ramspeck. This reference contemplates inter alia a time delay mechanism to automatically control the return stroke piston.

Keeping the foregoing comments in mind, the primary object of this invention is to produce a single cycle or cycle through type pneumatic fastener applying device.

A more specific object of this invention is to provide a fastener applying device of this type which will utilize considerably less air to effect the complete working cycle than the tools of the prior art.

It is a further object of this invention to provide a fastener applying device wherein the return stroke of the piston is automatically effected at the end of the 'working stroke, regardless of variations in air pressure or the like.

SUMMARY OF THE INVENTION In its broadest terms, this invention relates to an improved valving structure for automatically effecting the return stroke of the working piston of a fastener applying device immediately upon completion of the working stroke. This valving structure includes a manually actuated or responsive member which is effective, upon actuation, to initiate a cycle by causing the main valve to open, thereby admitting compressed air into the cylinder to drive the piston in its working stroke. A passage, including a check valve, receives compressed air only after the main valve has opened. This passage communicates with a pneumatically actuated member which, in response to compressed air in the passage, is effective to automatically close the main valve and to maintain it closed even though the manually actuated member remains in the actuated position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a fastener applying deviceembodying this invention.

FIG. 2 is an enlarged cross sectional view showing the check valve of this invention.

FIG. 2A is a schematic illustration of a modification of the check valve of this invention.

FIG. 3 is an enlarged cross sectional view along the line 3-3 of FIG. 1 and showing the components in the original position.

FIG. 4 is an enlarged cross sectional view similar to FIG. 3 showing the components after actuation of the manual trigger.

FIG. 5 is an enlarged cross sectional view similar to FIG. 3 showing the components at a later stage in the cycle of operation.

FIG. 6 is an enlarged cross sectional view similar to FIG. 3 showing the components upon release of the manual trigger.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, the general arrangement of components and mode of operation will be described. The fastener applying device includes a housing having a head portion indicated generally at 10 and a handle portion indicated generally at 12. The tool is adapted to be connected to a supply of fluid under pressure by means of a conventional fitting secured to the handle portion at 14. It will be observed that the handle portion is hollow so as to define the compressed air reservoir 16.

Within the head portion 10 of the tool is the sleeve 18 which defines the working cylinder of the tool. Slidably mounted within the sleeve 18 is the piston 20 which carries the fastener driver 22. The driver 22 may be provided with a plurality of flats 22a which provide a vent passage through the nosepiece of the tool. The piston driver assembly is movable in a cycle including a downward or working stroke, and an upward or return stroke.

The magazine structure indicated generally at 24 is effective to feed a fastener into position to be driven by the driver 22 on each working stroke of the piston driver assembly. The details of the magazine structure do not form a part of this invention. Reference may be had to U.S. Pat. No. 3,174,672 issued on Mar. 23, 1965 in the name of A. G. Juilfs for a detailed description of the magazine.

At the top of the cylinder sleeve 18 is the main valve indicated generally at 26. This main valve is movable to an open position to admit air under pressure into the cylinder sleeve 18 to drive the piston 20 and driver 22 in a working stroke. In the closed position of the main valve 26 (shown in FIG. 1) the portion of the cylinder sleeve 18 above the piston 20 is vented to atmosphere. In this position, the piston driver assembly may be returned to the initial position.

The main valve structure 26 and the pneumatic means for returning the piston 20 to its starting position do not form a part of this invention. Reference may be had to U.S. Pat. No. 3,170,487 issued on Feb. 23, 1965, in the name of A. G. Juilfs et al. for a full and detailed description of the main valve 26 and its operation. Similarly, reference may be had to U.S. Re. Pat. 26,262 issued on Sept. 5, 1967 in the name of A. G. Juilfs for a detailed description of the pneumatic return structure.

For present purposes, it should be noted that the main valve indicated generally at 26 is pneumatically actuated. That is, it is moved to the closed position by air under pressure in the passage 28. The flow of air under pressure into the passage 28 is controlled by the remote valve structure indicated generally in FIG. I at 30 and shown in more detail in FIGS. 3 through 6. Considering only FIG. 1 at the present time, actuation of the trigger 32 will be effective via the structure described in more detail hereinafter to vent the passage 28 to atmosphere. This will cause the main valve 26 to be opened by the air under pressure in the reservoir 16, thereby admitting air from the reservoir 16 into the sleeve 18 to drive the piston 20 in its working stroke.

When the piston 20 reaches its lowermost position at the end of the working stroke, air under pressure above the piston can pass through the passages 34 into the return reservoir 36 as explained in Re. Pat. No. 26,262. A portion of the air passing into the return reservoir 36 may pass via the passage indicated generally at 38 and check valve indicated generally in FIG. 1 at 40 (and shown in more detail in FIG. 2) to the valve structure 30. As will be explained in more detail hereinafter, this fluid passing past the check valve 40 is effective via the valve structure 30 to supply air under pressure to the passage 28, thereby closing the main valve 26.

As briefly indicated earlier and as explained in the United States patents incorporated herein by reference, the closing of the main valve 26 is effective to vent the cylinder sleeve 18 above the piston 20 to atmosphere; the air stored in the return reservoir 36 is then effective via the ports 42 to return the piston to its uppermost position.

It will be understood that all of the foregoing operations occur at very high speed and completely automatically once the operator actuates the manual trigger 32. That is, the main valve 26 opens, the piston 20 and driver 22 are driven in a working stroke, the main valve 26 is then closed, and the piston 20 and driver 22 returned to their starting position even though the manual trigger 32 remains actuated. A second cycle can be carried out only by releasing the trigger 32 and then depressing it once again.

Turning now to FIGS. 3 through 6, the components and operation of the valve structure 30 will be described in more detail.

The valve structure is mounted in the fastener housing so as to extend through the reservoir 16. To this end, it will be noted that the housing of the handle portion 12 is provided with the coaxial bores 42, 44, and 46 of increasingly greater diameter. By this expedient, the entire valve structure 30 may be placed in the tool from the top of the handle, and held in place by a suitable cap.

Disposed within the bore 42 is the spacing sleeve 48 which is provided with the relieved area 48a. The bore 46 is provided with the insert sleeve 50. This sleeve may be provided with the sealing O-rings 52 and 54. The exterior of the sleeve is provided with the relieved area 50a and the interior with the relieved area 50b, and a plurality of radial passages 56 extending in the region of the relieved areas.

Slidable within the bore 44 and the interior of the spacing sleeve 50 is the remote valve sleeve indicated generally at 58. It will be seen that the lower portion 58a of the valve sleeve is of a larger diameter than the upper portion 58b. It will be seen that the portion 58a and 58b are each provided with O-rings as is conventional in the art, so that a sealing engagement is'maintained between the portion 58a and the bore 44, and between the portion 58b and the bore in the sleeve 50.

The interior of the valve sleeve 58 is provided with a series of stepped bores. The lowermost bore 60 is of the largest diameter. Immediately above the bore 60 is the bore 62 of a slightly smaller diameter. The bore 64 is of a still smaller diameter than the bore 62, and at the top is the counterbore 66. It will also be seen that the central portion of the sleeve 58 is provided with the radial apertures 68 which communicate between the interior of the valve sleeve and the reservoir 16.

Slidable within the valve sleeve 58 is the stern indicated generally at 70. The stem 70 includes a portion 72 of reduced diameter with the D ring seal 74 and 76 at the lower and upper ends respectively of the relieved portion. The lower portion 78 of the stem is of enlarged diameter but includes a relieved portion 80 between the o-ring seals 82 and 84.

The stem also includes the end portion 86 which extends through the bottom of the housing and is actuated by the manual trigger 32.

The initial position of the components just described is illustrated in FIG. 3. The stem 70 and sleeve 58 are each in their lowermost positions. In this condition, fluid under pressure in the reservoir 16 passes through the radial ports 68 into the bore 62 in the sleeve 58. This fluid passes around the O-ring 74 into the bore 64, thr ugh the ports 69 into the relieved area 50b on the int rior of the spacing sleeve, through the ports 56 into the space between the relieved area 50a and the bore 46,;thence through the passage 28 to the space above the main valve 26. This air under pressure is effective to maintain the main valve in its closed position.

Upon actuation of the trigger 32, the valve stem 70 moi'es upwardly to the position shown in FIG. 4. It will be observed that this motion brings the C ring 74 into sealing engagement with the bore 64, thereby cutting off the further passage of fluid under pressure to the passage 28. Shortly after the O-ring 74 engages the lower edge of the bore 64, the O-ring 76 moves into the relieved area 66. This relieved area 66 is in communi cation with atmosphere via a suitable port which would be provided in the cap, but is not shown in these FIGS. Thus, the air under pressure above the main valve is free to pass via the passage 28, the passage 56, and the passage 69 into the bore 64. It may then pass around the ,O-ring 76 and to atmosphere. This exhausting of the fluid under pressure above the main valve will cause the main valve to be opened. This, of course, admits fluid under pressure from the reservoir 16 into the upper end of the working cylinder 18 driving the piston and the driver 22 in a downward or working stroke.

As explained earlier, when the piston 20 reaches the bottom of the working stroke, the fluid under pressure in the cylinder sleeve 18 can pass through the ports 34 into the return reservoir. The return reservoir communicates via the passage 38 and check valve 40 with the bore 44 below the enlarged portion 58a of the valve sleeve 58. This air under pressure acting on the underside of the enlarged portion 58a of the valve sleeve will cause it to move upwardly to the position shown in FIG. 5. At this point, the stem 70 and sleeve 58 are in the same position relative to each other as they occupied in FIG. 3. That is. the O-ring 76 is in sealing engagement with the upper portion of the bore 64 while the O-ring 74 is disposed within the bore 62. Thus, fluid under pressure can pass from the reservoir 16 through the passages 68, past the O-ring 74, through the ports 69 and 56, and the passage 28 to the space above the main valve 26. As explained earlier, this is of course effective to move the main valve to the closed position.

Thus, it will be observed that upon actuation of the manual trigger, the main valve was caused to open. At the bottom of the working stroke, air under pressure was utilized via the valving structure of this invention to automatically close the main valve even though the trigger remained actuated.

It will be understood by the skilled worker in the art that when the piston 20 is in the uppermost position, the entire cylinder sleeve 18 below the piston is vented to atmosphere via the nose piece of the tool. (The flats 22a on the driver maintain this vent to atmosphere open until the piston is seated on the stop at the bottom of its stroke.) This of course means that the return reservoir 36 is vented to atmosphere via the ports 42 and the nose piece of the tool.

In order to maintain the main valve in the closed position, it is necessary to provide a check valve 40 in the passage 38, so that when the return reservoir is vented to atmosphere, the compressed air actuating the sleeve 58 will be held captive.

The check valve is shown in more detail in FIG. 2. It includes a single diameter bore 90 extending through the housing. Received within the bore 90 is the valve body 92 which is provided with the shaped grooves 94 and 96. The port 98 in the valve body 90 extends from the relieved area 94 to the center of the valve body 92. A plurality of radial passages extend from the relieved area 96 into the bore 98. An O-ring 102 will be fitted within the relieved groove 96.

The bore 90 containing the check valve communicates with the return reservoir 36 via the portion 38a of the passage 38, and with the bore 44 of the valve structure 30 via the portion 38b. Thus, compressed air from the return reservoir 36 may pass through the passage 38a into the relieved groove 94, through the passages 98 and 100, past the O-ring 102, into the relieved groove 96, and finally through the passage 38b into the bore 44. When the return reservoir 36 is exhausted to atmosphere, the fluid in the passage 38a and passages 98 and 100 will also be vented to atmosphere. However, the pressure of the air in the passage 38b and relieved groove 96 will compress the O-ring 102 inwardly to form a seal preventing escape of the air. Thus, the compressed air holding the sleeve 58 in the position shown in FIG. 3 is trapped.

When the operator releases the manual trigger 32, the valve stem 70 will be moved to the lowermost position shown in FIG. 6. It will be observed that during this movement, the O-ring 76 remains in sealing engagement with the bore 64 above the port 69, thereby preventing any exhaust of the air holding the main valve closed.

It will also be observed that the O-ring 82 at the bottom of the stem moves into the relieved area 48a. This opens a vent to atmosphere to bleed off the air previously held captive in the bore 44. The air is now free to exhaust to atmosphere via the relieved area 80, past the O-ring 82 and relieved area 48a, and via the passages 104 which may be radial grooves or the like adjacent the stem 86. The exhausting of this captive air to atmosphere will permit the sleeve 58 to be returned to the lowermost position shown in FIG. 1 by virtue of the differential diameter between the portion 58a and 58b. In this condition, the tool is now ready to be cycled again.

It should be apparent to the skilled worker in the art that if the check valve is rendered ineffective (so that the air in the passage 38 is exhausted when the return reservoir 36 is vented), the fastener applying device will automatically, repetitively cycle. That is, with the components in the position shown in FIG. 5, the exhaust of the air in the passage 38 will cause the sleeve 58 to be moved downwardly, bringing the components to the position shown in FIG. 4 and causing the main valve to reopen.

Similarly, blocking the passage 38 will permit the tool to be operated in the conventional manner described earlier. The piston will move downwardly upon actuation of the trigger, and will remain at the bottom of its stroke until the trigger is released since the passage 38a will be blocked from the passage 38b.

Both blocking of the passage 38 and rendering the check valve ineffective may be accomplished in a variety of ways. For example, the valve body 92 can be elongated and slidable in the bore 90. In this case, as shown schematically in FIG. 2A, the body 92 would be provided with a check valve portion 92a, a straight through port portion 92b, and a sealing or blocking portion 92c.

It is believed that the foregoing constitutes a full and complete disclosure of this invention, and no limitations are to be inferred or implied except as specifically set forth in the claims which follow.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a fastener applying device adapted to be connected to a supply of fluid under pressure and having a cylinder with a working piston slidably mounted therein for movement in a cycle including a working and a return stroke; means for moving a fastener into position to be driven on each working stroke; and a pneumatically actuated main valve which in a first position admits fluid under pressure into said cylinder above said piston to move said piston in said working stroke and in a second position exhausts said cylinder above said piston to atmosphere; the improved structure for controlling actuation of said main valve comprising:

a. valve means communicating with said main valve,

said valve means having i. a manually actuatable member movable from an inoperative position to an operative position effective to cause said main valve to be pneumatically opened;

ii. a pneumatically actuated member movable from a first position to a second position effective to cause said main valve to be pneumatically closed even though said manually actuable member remains in said operative position;

b. a pneumatic passage for establishing communication between at least a portion of said pneumatically actuated member and said fluid under pressure; and

c. a check valve in said passage for admitting fluid under pressure to actuate said pneumatically actuated member and for preventing release of said fluid under pressure through said passage.

2. The improved structure claimed in claim 1 wherein said pneumatically actuated member is normally biased to said first position.

3. The improved structure claimed in claim 1 wherein return of said manually actuatable member to said inoperative position is effective to release said fluid under pressure in said passage.

4. The improved structure claimed in claim 1 wherein said manually actuatable member and said pneumatically actuated member comprise a cooperating, telescoping valve stem and a valve sleeve.

5. The improved structure claimed in claim 1 wherein said main valve is normally in communication via said valve means with said supply of fluid under pressure, and wherein movement of said manually actuatable member to said operative position is effective to prevent communication between said main valve and said supply of fluid under pressure and establish communication between said main valve and atmosphere.

6. The improved structure claimed in claim 5 wherein movement of said pneumatically actuatable means to said second position is effective to prevent communication between said main valve and atmosphere and to reestablish communication between said main valve and said supply of fluid under pressure whereby to cause said main valve to be pneumatically closed.

7. The improved structure claimed in claim 1 wherein said pneumatic passage communicates with said fluid under pressure only after said main valve has been pneumatically moved to said first position.

8. The improved structure claimed in claim I wherein said pneumatic passage communicates only with fluid under pressure admitted to said working cylinder.

9. The improved structure claimed in claim 1 including means for rendering said check valve ineffective to permit release of said fluid under pressure through said passage, whereby said fastener applying device will automatically reciprocate so long as said manually actuatable member is in said operative position.

10. The improved structure claimed in claim 1 including means for blocking said passage.

11. In a fastener applying device adapted to be connected to a supply of fluid under pressure and having a cylinder with a working piston slidably mounted therein for movement in a cycle including a working and a return stroke; means for feeding a fastener into position to be driven on each working stroke; a pneumatically actuated main valve which in a first position admits fluid under pressure into said cylinder above said piston to move said piston in said working stroke and in a second position exhausts said cylinder above said piston to atmosphere; and manually responsive valve means effective, upon actuation, to cause said main valve to be pneumatically opened; the improved structure for automatically causing said main valve to be pneumatically closed even though said manually responsive valve means is actuated and for maintaining said main valve closed until said manually responsive valve is released and actuated again, comprising:

a. a passage communicating with a portion of said cylinder for receiving fluid under pressure from said cylinder;

b. means associated with said passage and actuated by said fluid under pressure for causing said main valve to be closed; and

c. a check valve in said passage for admitting fluid under pressure to actuate said means for closing said main valve and for preventing release of said fluid under pressure therefrom.

12. The improved structure claimed in claim 11 

1. In a fastener applying device adapted to be connected to a supply of fluid under pressure and having a cylinder with a working piston slidably mounted therein for movement in a cycle including a working and a return stroke; means for moving a fastener into position to be driven on each working stroke; and a pneumatically actuated main valve which in a first position admits fluid under pressure into said cylinder above said piston to move said piston in said working stroke and in a second position exhausts said cylinder above said piston to atmosphere; the improved structure for controlling actuation of said main valve comprising: a. valve means commuNicating with said main valve, said valve means having i. a manually actuatable member movable from an inoperative position to an operative position effective to cause said main valve to be pneumatically opened; ii. a pneumatically actuated member movable from a first position to a second position effective to cause said main valve to be pneumatically closed even though said manually actuable member remains in said operative position; b. a pneumatic passage for establishing communication between at least a portion of said pneumatically actuated member and said fluid under pressure; and c. a check valve in said passage for admitting fluid under pressure to actuate said pneumatically actuated member and for preventing release of said fluid under pressure through said passage.
 2. The improved structure claimed in claim 1 wherein said pneumatically actuated member is normally biased to said first position.
 3. The improved structure claimed in claim 1 wherein return of said manually actuatable member to said inoperative position is effective to release said fluid under pressure in said passage.
 4. The improved structure claimed in claim 1 wherein said manually actuatable member and said pneumatically actuated member comprise a cooperating, telescoping valve stem and a valve sleeve.
 5. The improved structure claimed in claim 1 wherein said main valve is normally in communication via said valve means with said supply of fluid under pressure, and wherein movement of said manually actuatable member to said operative position is effective to prevent communication between said main valve and said supply of fluid under pressure and establish communication between said main valve and atmosphere.
 6. The improved structure claimed in claim 5 wherein movement of said pneumatically actuatable means to said second position is effective to prevent communication between said main valve and atmosphere and to reestablish communication between said main valve and said supply of fluid under pressure whereby to cause said main valve to be pneumatically closed.
 7. The improved structure claimed in claim 1 wherein said pneumatic passage communicates with said fluid under pressure only after said main valve has been pneumatically moved to said first position.
 8. The improved structure claimed in claim 1 wherein said pneumatic passage communicates only with fluid under pressure admitted to said working cylinder.
 9. The improved structure claimed in claim 1 including means for rendering said check valve ineffective to permit release of said fluid under pressure through said passage, whereby said fastener applying device will automatically reciprocate so long as said manually actuatable member is in said operative position.
 10. The improved structure claimed in claim 1 including means for blocking said passage.
 11. In a fastener applying device adapted to be connected to a supply of fluid under pressure and having a cylinder with a working piston slidably mounted therein for movement in a cycle including a working and a return stroke; means for feeding a fastener into position to be driven on each working stroke; a pneumatically actuated main valve which in a first position admits fluid under pressure into said cylinder above said piston to move said piston in said working stroke and in a second position exhausts said cylinder above said piston to atmosphere; and manually responsive valve means effective, upon actuation, to cause said main valve to be pneumatically opened; the improved structure for automatically causing said main valve to be pneumatically closed even though said manually responsive valve means is actuated and for maintaining said main valve closed until said manually responsive valve is released and actuated again, comprising: a. a passage communicating with a portion of said cylinder for receiving fluid under pressure from said cylinder; b. means associated with said passage and actuated by said fluid under pressure for causing said mAin valve to be closed; and c. a check valve in said passage for admitting fluid under pressure to actuate said means for closing said main valve and for preventing release of said fluid under pressure therefrom.
 12. The improved structure claimed in claim 11 wherein said means associated with said passage includes pneumatically actuated valving structure.
 13. The improved structure claimed in claim 11 including means for rendering said check valve ineffective to permit release of said fluid under pressure through said passage, whereby said fastener applying device will automatically reciprocate so long as said manually responsive valve means remains actuated.
 14. The improved structure claimed in claim 11 including means for blocking said passage. 